Trammel



oct. 1'7, 1939. G, A. R PAE-GE 2,1%,681

TRAMMEL Filed June l, 1959 `ATTORNEY- Patented Oct. 17, 1939 UNITED STATES ATENT OFFECE 2 Claims.

This application relates to measuring or drafting instruments known as beam Compasses or trammels.

The principal object is to provide a beam compass or trammel of extremely simple construction for precise measurements and which is so formed that though its slide blocks may easily be moved along the beam, they will, when desired, fix themselves so rmly on the beam that they and the scriber points carried thereby will be rigid and firm with respect to the beam whereby to eliminate objectionable creeping of the point with respect to the beam. The compass is formed to be free of objections arising due to expansion or contraction of parts, on temperature or moisture change, causing dead movement.

An embodiment of the invention is disclosed in the appended drawing. In this drawing:

Fig. l is a cross section or end View;

Fig. 2 is a side view with one of the sliding blocks shown as having a scriber point therein;

Fig. 3 is a top plan view with both blocks shown as having scriber points therein.

The beam compass hereof comprises a beam I of wood, metal or other materials, formed solid or tubular as desired, and of the cross section of a pentagon or the like, the beam having a iat top II and having sides comprising portions I2 which are square to the top and portions I4 which are arranged at oblique angles to the top to meet in an apex line I5.

Slidably mounted on the beam are the slide blocks. Each of these consists of a sheet metal body having sides shaped to t closely around the oblique sides of the beam with necessary clearance for expansion between the parallel sides and thus each slide block has two parallel portions IB and two inclined portions Il which meet in an apex line I8 disposed at the apex line of the beam. Aligned slots in the side portions I6 of the slide blocks receive stub shafts or bearings 2| on the ends of knurled rollers 22 which are thus journaled in the slide blocks with their axes oblique to the portions I4 and I'I of the beam and blocks.

The rollers 22 are arranged to roll along the flat top of the beam. In each block is a spring 23 for pressing the roller against the flat topl of the beam and for wedging the inclined surfaces II of the block against the inclined surfaces I4 of the beam and each spring also operates as a means for releasably holding a scriber point or pencil rmly in the slide block, all in a manner that will now be described.

Each spring consists of a nat leaf having its (Cil. 33-15S) center cut out to provide side portions 24 and end portions 25 and 26. The side portions 24 have lugs 21 fitting in the slots 20 and resting on the bearings 2l. The end portions 25 and 26 fit under cross pins 28 which connect the side portions I8 of the blocks at their ends. The end portion 26 has a nger grip forming extension which may be. pressed towards the flat top ofV the beam for releasing a scriber point or pencil 29 disposed in aligned holes 30 formed in the portions I6 of the slide blocks. The scriber point is normally wedged into V-shaped portions 3| of such holes by bent portions 32 of the springs, for the spring is so formed that its ends tend to move toward pins 28 and its center lugs 21 tend to move towards the beam I0.

When the parts are mounted as shown, the slide block will be seated firmly, with its pointer, on the beam and movement of the beam and its pointer will not be accompanied by creeping or objectional lateral shifting of the pointer with respect to the beam. The block may be moved longitudinally of the beam without disturbing the setting of the pointer with respect to the block merely by pushing or pulling the block along the beam without touching the ringer grip, using the knurled nut as a thumb roller for ne setting.

The block spring holds the pointer firm with respect to the block, but may be easily pressed to release the pointer.

I claim:

l. A beam compass or trammel comprising a beam having a flat top and having sides having portions squared to the topand portions arranged at oblique angles to the top to meet in an apex line, and slide blocks comprising sheet metal bodies, each having sides shaped to t closely around the edges of the beam and thus comprising two parallel portions and two inclined portions which meet in an apex line disposed at the apex line of the beam, a roller in each block journalled in its sides and arranged to roll along the flat top of the beam, and a spring in each block for pressing the roller against the flat top of the beam and for wedging the inclined surfaces of the block against those of the beam, and a scriber holder in the block, comprising a bent portion of the spring formed to wedge the scriber into V shaped parts of holes in the parallel sides of the block, the holes being in a line transverse to the long axis of the beam.

2. A beam compass or trammel comprising a beam having a flat top and having sides having portions squared to the top and portions arranged at oblique angles to the top to meet in an apex line, and slide blocks comprising sheet metal bodies, each having sides shaped to t closely around the edges of the beam and thus comprising tWo parallel portions and two inclined portions Which meet in an apex line disposed at the apex line of the beam, a roller in each block journalled in its sides and arranged to roll along the flat top of the beam, and a spring in each block for pressing the roller against the flat top of the beam and for Wedging the inclined surfaces of the block against those of the beam, and a scriber holder in the block, comprising a bent portion of the spring formed to Wedge the scriber into V shaped parts of holes in the parallel sides of the block, the holes being in a line transverse to the long axis of the beam, the block having at its ends abutments under Which are the ends of the spring, the latter passing over the roller, and having a nger grip extending beyond the end of the block, with the bent portion of the spring and the block holes being between the roller and that end of the block nearer the 10 finger grip of the spring.

G. A. REINHOLD PAEGE. 

